The present invention relates to elevator installations with vertical elevator shafts arranged adjacent to one another and individually movable elevator cars able to carry out a shaft change, as well as to a method of operating such elevator installations.
Every elevator installation requires a certain proportion of space in a building depending on the traffic volume. The larger the traffic volume and the higher the building, the more space the elevator installation needs in relation to usable area (net useful area) of the building. The performance of an elevator installation can be expressed by the so-called handling capacity. The handling capacity indicates how many persons can be transported per minute in the case of high traffic volume, for example at the beginning of a working day in an office building.
It is therefore of concern to minimize the space requirement of an elevator installation. This is achieved by measures which allow reduction in the handling capacity per area unit or volume unit of the space needed for the elevator installation.
One route to increasing handling capacity without demanding an excessive amount of space consists in enabling several elevator cars to run simultaneously in an elevator shaft or in providing, in accordance with the paternoster principle, an upward elevator shaft and a downward elevator shaft in which several elevator cars move in fixed relationship at a common, encircling support means. In such elevator installations it is possible to achieve, by suitable measures, an optimally short time between departure of a first elevator car and arrival of a further elevator car.
An elevator system 10 operating according to the paternoster principle is schematically shown in FIG. 1 in a sectional illustration, wherein in this elevator system 10 the elevator cars move, in departure from the paternoster elevator, individually. Two vertical elevator shafts 11.1 and 11.2 are provided, in which several elevator cars 16, which are driven individually or in common, move. Changeover points are provided at the upper and lower shaft ends so as to enable horizontal displacement of the elevator cars 16. The elevator cars 16 travel upwardly on the left and downwardly on the right. The individual floors are characterized by the reference numerals 13.1-13.5. Displacement from one shaft to another shaft requires time, which limits the handling capacity of the elevator system 10.
There are various approaches for arrangement of parallel elevator shafts of an elevator installation, for changing over of elevator cars from one elevator shaft to another elevator shaft (shaft change) and for providing and operating more than only one elevator car in an elevator shaft.
A possible arrangement with two elevator shafts and a changeover zone is described in U.S. Pat. No. 3,658,155. The elevator cars move individually along rail equipment.
It is a disadvantage of the known elevators with several elevator shafts that displacement of an elevator car to another shaft is very complicated in mechanical terms and frequently takes place only slowly. A limit is thus imposed on handling capacity in the case of increased traffic volume. It has proved that the time between departure of a first elevator car and arrival of a further elevator car is substantially dependent on the time used for displacing (shaft change) an elevator car in the elevator shaft.
An arrangement which comprises four elevator shafts with connecting passages at the upper end and lower end is known from the European patent application with the title “Sicherheitseinrichtung bei Multimobil-Aufzugsgruppen”, which was published under the number EP 769469-A1. The advantages or disadvantages of such multi-mobile elevator groups with respect to handling capacity are not dealt with in the cited application.
An elevator installation with elevator cars having an autonomous linear drive which is disposed at the car and makes it possible for the elevator cars to independently move in the elevator shafts in a vertical direction is known from the European patent application published under the number EP 1367018-A2. The elevator cars are constructed in such a manner that it is possible to also reliably manage a transverse displacement.
The handling capacity of such an elevator installation can be increased, as was sought at different times, in that the changeover mechanism, which is decisive for the shaft change, is improved. However, the mechanical outlay for achieving a more rapid shaft change is comparatively large.